Various methods of treating hops and its extracts are known. In accordance with these methods the alpha acids and beta acids are extracted from the hop by an organic solvent. For this extraction a solvent may be used, inter alia, hexane, pentane, petroleum ether, methylcyclohexane, octane, isooctane, chloroform, methylene chloride, trichlorethylene, carbon tetrachloride, ethylene chloride, benzene, toluene, xylene, acetone, methanol, ethanol, isopropanol or dibutyl ether. This extraction is effected with or without recovery of the aromatic components of the hops and of polyphenol compounds such as tannins and the like. The extraction yield with the above solvents is a mixture of at least 95% alpha acids and beta acids. The determination of the different compounds in the hops and its extracts is effected by conductimetric methods or by gas chromatography or by using an ion exchange resin.
Of course the hops and its extracts must be treated by a method which permits the maximum utilization of the characteristic bitter substances contained in the hop.
The present invention relates to a process of preparing an isomerized hop extract with maximum utilization of the normally present compounds of the hops, namely the alpha-acids such as humulone, cohumulone, adhumulone, prehumulone, and posthumulone, and the beta acids such as lupulone, colupulone, adlupulone, prelupulone, and postlupulone, to convert them to useful bittering substances fully and legally acceptable for human consumption. This extract can be added to beer in the course of manufacture, during the step of the boiling of the wort or after such boiling, during the main fermentation or toward the conclusion of the secondary fermentation.
The advantages of the invention are numerous:
It makes it possible to reduce the non-uniformity in manufacture due to variations in quality of the starting products. PA1 it results in a saving due to the recycling of the treatment products (in particular the ethanol). PA1 it is excellently adapted to the manufacture of beer.